1. Field of the Invention
The present invention generally relates to an image processing apparatus and an image forming apparatus having means for preventing an image formation of a special document such as a paper money, a security paper (policy form) or the like.
2. Description of the Related Art
With advanced development in an image processing technology and image forming technology, it has become capable of performing an image formation elaborately such that a copied paper money and a copied security paper printed by a color copy machine are not easily distinguishable from a real paper money and a real security paper. For this reason, a technique has been developed to discriminate a special document such as a paper money to prevent a copy of the special document, and a copy machine having a special document discriminating function has been developed by providing a function to discriminate a special document to a copy machine.
As such a copy machine, there is known by Japanese Laid-Open Patent Application No. 2001-292315 a copy machine, in which a paper money recognition control circuit recognizes, when a paper money as a special document is read by a scanner, image data of the read image as an image of a paper money; a notification is sent to a third party that a copy of a special document is being performed; a counter value for setting a time period from a power supply to a start of a starting process is increased; an error message is displayed on an LCD display part; and all processes are stopped.
Additionally, there is known by Japanese Laid-Open Open Patent Application No. 2001-144940 a copy machine as a copy machine having a special document discriminating function, in which a forgery determination processing module of a scanner driver compares image data generated by reading a document by a scanner with image data of a specific document so as to determine a level of coincidence; and a forgery prevention control module processes the image data generated by a scanner base on a result of the determination.
Further, there is known a copy machine by Japanese Laid-Open Patent Application No. 6-125459, which stores feature data of special documents of which copy is prevented in accordance with kinds of images of the special documents; extracts a feature image part from the input image data; compares the image data of the extracted image part with the stored feature data; prohibits a copy operation if a similarity as a result of the comparison corresponds to a predetermined first similarity; and providing a mark onto a recording paper if the similarity corresponds to a second similarity.
The invention disclosed in the above-mentioned Japanese Laid-Open Patent Application No. 2001-292315 prohibits a copy operation when an original document is determined as a special document. The invention disclosed in the above-mentioned Japanese Laid-Open Patent Application No. 2001-144940 processes copy image data when an original is determined as a special document. The invention disclosed in the above-mentioned Japanese Laid-Open Patent Application No. 6-125459 prohibits a copy operation or performs marking on a print paper in accordance with a degree of determination that an original document is a special document.
As mentioned above, the invention disclosed in each of the above-mentioned patent documents discriminates a special document, and, thereafter, takes measures for a forgery of the special document such as prohibiting a copy or processing a copy image based on a result of the discrimination. That is, although there is a difference in an accuracy of discrimination, each of the copy machines disclosed in the above-mentioned patent documents takes measures for a forgery of a special document on the assumption that the discriminating function of a special document is functioning normally.
However, since a copy machine having a special document discriminating function is capable of making a copy of a normal document without any restriction, if the special document discriminating function is made inactive, a special document may be copied in the same manner as a normal document.
Additionally, in recent years, a special document has not been limited to a conventional paper money or security paper, and has been expanded to many kinds of papers such as a gift certificate, a toll-road ticket, etc. However, the copy machines with a special document discriminating function disclosed in the above-mentioned patent documents are made in consideration of specific special documents, and are not oriented to a copy machine having a special document discriminating function, which is capable of acting according to various kinds of special documents.
Further, in recent years, users of copy machines tend to request preferably a copy machine having a cost advantage that has only necessary functions in accordance with circumstances of a copy machine of user's own use. However, since the copy machines having a special document discriminating function disclosed in the above-mentioned patent documents are always provided with the special document discriminating function as a general function, a function change cannot be made in response to the user', s needs.